The present invention relates to the detection of hydrazine compounds and, more particularly, is directed toward real-time, passive detection of hydrazine compounds using benzaldehyde and its derivatives.
2. Description of the Prior Art:
Hydrazine is an extremely toxic chemical which is used in industry as a blowing agent for blow molded plastic products, for the synthesis of agricultural products, as a oxygen scavenger agent for water treatment to inhibit corrosion, pharmaceutical applications and as a rocket propellant. Due to the high toxicity of hydrazine, employers must meet specified standards for monitoring exposure levels of hydrazine for all employees who might be exposed. Currently, hydrazine monitoring is accomplished by use of expensive instrumentation which is transported to various facilities for non-continuous monitoring of air and water. Such instrumentation requires calibration regularly and is not particularly adapted for individual monitoring. A citric acid dosimeter collects analyte data, but not in real-time. The use of para -N, N-dimethylaminobenzaldehyde is a known wet chemical method, but it is not used as a dosimeter.
U.S. Pat. No. 3,455,656 discloses colorimetric detection of hydrazine compounds by means of a solid carrier that is impregnated with solutions containing a silicic acid and a molybdic acid. These methods have not been demonstrated for real-time, passive detection.
There are few commercial real-time detectors or acceptable techniques available for detection of hydrazine exposure at threshold limiting values (100-500 parts-per-billion, depending upon the specific hydrazine to be detected). Passive electrochemical techniques have not proven reliable; liquid sorbent badges lack the required precision and accuracy; strong acids on supports are not applicable to monomethylhydrazine; and collection on citric acid coated disks does not provide real-time analysis.
A need exists for a simple, inexpensive and reliable method and device which provides a passive, real-time visual indication of hydrazine exposure as well as individual personnel monitoring of exposure to hydrazine.